In a well used for hydrocarbon extraction, substances may be present that inhibit operation of the well. These substances may be bound up in strata being excavated to form the well and/or the substances may migrate from adjacent strata. One example of such a substance is hydrogen sulfide. Conventional mechanisms for determining a level of hydrogen sulfide in drilling fluid within a well require extraction of drilling fluid for measurement, require a relatively length measurement process, are labor intensive, and/or suffer from other drawbacks.